1. Field
The present application relates generally to wireless communications, and more specifically to management of high-speed dedicated physical control channel decoding in soft handover procedures.
2. Background
The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) represents a major advance in cellular technology and is the next step forward in cellular 3G services as a natural evolution of Global System for Mobile communications (GSM) and Universal Mobile Telecommunications System (UMTS). The LTE physical layer (PHY) is a highly efficient means of conveying both data and control information between an evolved NodeB (eNB) and mobile entities (MEs), such as, for example, access terminals (ATs) or user equipment (UE). The LTE PHY employs some advanced technologies that are new to cellular applications. These include Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) data transmission. In addition, the LTE PHY uses Orthogonal Frequency Division Multiple Access (OFDMA) on the downlink (DL, also called “forward link”) and Single-Carrier Frequency Division Multiple Access (SC-FDMA) on the uplink (UL, also called “reverse link”). OFDMA allows data to be directed to or from multiple users on a subcarrier-by-subcarrier basis for a specified number of symbol periods.
Examples of older wireless communication systems widely deployed to provide various types of communication content such as voice and data include Code Division Multiple Access (CDMA) systems, including CDMA2000, Wideband CDMA, Global System for Mobile communications (GSM), and Universal Mobile Telecommunication System (UMTS). These wireless communication systems and LTE systems generally use different radio access technologies (RATs) and communication protocols, operate at different frequency bands, provide different quality of service (QoS) and offer different types of services and applications to the system users.
Multiple mode mobile entities that are capable of operating on multiple heterogeneous wireless communication systems are commonly available, for use with different communication systems. For example, many geographic areas are now served by multiple wireless communication systems, each of which can utilize one or more different air interface technologies. To increase versatility of wireless terminals in such a network environment, there recently has been an increasing trend toward multi-mode wireless terminals that are able to operate with multiple radio technologies. A multi-mode implementation may enable a terminal to select a system from among multiple systems in a geographic area, each of which may utilize different radio interface technologies, and subsequently communicate with one or more chosen systems. In the alternative, or in addition, a heterogeneous communications system may include access points transmitting at various different power levels, for example lower-power femtocells or picocells interspersed with higher-power macrocells. In addition, access points, for example lower-power access points, may be deployed in an ad hoc or unplanned manner within a system. Consequently, different systems and access points may be accessible to the same ME, according to some order of preference of system operator identity and system technology. These conditions create new issues and challenges in efficiently managing multiple modes for user equipment, terminals and other nodes, for example in soft handover contexts wherein an access terminal may be communicating with diverse access points.